The Treaty of Alcáçovas (also known as Treaty or Peace of Alcáçovas-Toledo) was signed on 4 September 1479 between the Catholic Monarchs of Castile and Aragon on one side and Afonso V and his son, Prince John of Portugal, on the other side.

It put an end to the War of the Castilian Succession, which ended with a victory of the Castilians on land and a Portuguese victory on the sea. The four peace treaties signed at Alcáçovas reflected that outcome: Isabella was recognized as Queen of Castile while Portugal reached hegemony in the Atlantic Ocean.

The treaty intended to regulate:

The renunciation of Afonso V and Castilian Monarchs to the Castilian throne and Portuguese throne, respectively

The division of the Atlantic Ocean and overseas territories into two zones of influence

The destiny of Juana de Trastámara

The contract of marriage between Isabella, the eldest daughter of the Catholic Monarchs, with Afonso, heir of Prince John. This was known as Tercerias de Moura, and included the payment to Portugal of a war compensation by the Catholic Monarchs in the form of marriage dowry.

The pardon of the Castilian supporters of Juana